Protocol for a mixed methods process evaluation of the Smoking Treatment Optimisation in Pharmacies (STOP) trial

IntroductionAssessing the fidelity of complex behavioural interventions and examining the contextual reasons why such interventions succeed, or fail are important activities but challenging and rarely reported. The Smoking Treatment Optimisation in Pharmacies (STOP) trial is a cluster randomised trial evaluating the effectiveness of a complex intervention to optimise the National Health Service (NHS) Stop Smoking Service delivered in community pharmacies. This complex intervention comprises a training package for pharmacy staff involving motivational interviewing and communication skills aimed at increasing smoking cessation knowledge and proactive client engagement. We report on a process evaluation which was planned alongside the trial to offer findings that will assist in the interpretation of the main trial results and help inform potential implementation in community pharmacy settings on a wider scale. Methods and analysisQuantitative data on recruitment and retention process of pharmacies, pharmacy staff and service users has been collected during the trial along with data on dose and fidelity of the intervention delivery from participating intervention arm pharmacies to identify potential implementation issues. Simulated client data on behaviour change skills and display of intervention materials from both control and intervention pharmacies is being assessed. These data will be combined with qualitative data; including adviser-smoker consultation recordings that provide a snapshot of behaviour skills delivery by stop smoking advisers and semi-structured interviews with pharmacy staff and services users from the intervention arm. DiscussionPublished protocols for process evaluations of complex health interventions are still rare despite increasing funding for this work to facilitate understanding of trial outcomes from an implementation perspective. This mixed methods protocol will contribute to the developing literature around the conduct of process evaluation and the value they add to health services research. Trial registration number ISRCTN16351033. Strengths and limitations of this studyO_LIA planned mixed methods process evaluation that draws together data from different sources to help explain the trial results and establish the feasibility of scaling this complex intervention up in community pharmacy settings. C_LIO_LIA strength is the use of a previously tested mystery shopping method to assess fidelity of skills performance at the pharmacy counter C_LIO_LIThe process evaluation relies on willing pharmacy staff and service users involved in the trial to collect some of the data, which may introduce bias. C_LIO_LIThis paper also provides a detailed example of how to use the MRC framework for process evaluation of complex interventions to design an extensive process evaluation within trial settings. C_LI